The Wool Journey Part 3: wool attributes – length, crimp and lustre

The Wool Journey Part 3: wool attributes – length, crimp and lustre

Length is less relevant to the processor than to the breeder!  After all, the breeder will be expecting to show animals in full fleece in all their glory, while the processor has to sort out the fibres and put them through machines.  So the processor can rely on some fibres breaking as they are processed and also may chop up some fibre to make it more usable, particularly if it is thick and strong.  A hand-spinner might wish to spin individual long locks together and craft workers may use individual locks as part of a design (e.g. wedding dress).

A lovely example of the use of Lincoln Longwool locks in the skirt and felt in the bodice is Louise Fairburn’s wedding dress which caused quite a stir of publicity in 2009, even reaching the Daily Mail!

Image courtesy of The Risby Flock of Lincoln Longwools

However, length will also determine the amount of fleece grown by the animal each year, so longwool sheep, such as Cotswold or Wensleydale, and suri alpacas, produce considerably more wool than downland sheep, such as Southdowns, or huacaya alpacas.  Size is also relevant: smaller sheep, for example Shetlands, produce less weight of fleece than larger sheep such as the giant Oxford Down, which is the largest British breed sheep by weight, though the weight of fleece from a large longwool, such as the Devon and Cornwall, will actually weigh much more than from an Oxford Down. 

At The Natural Fibre Company we strongly advise breeders of longwool sheep to shear twice a year, both for sheep welfare (subject to weather conditions and hardiness) and for quality of fibre: 

–          in terms of welfare, as sheep put on a layer of insulating brown fat within 24 hours of shearing and longwools will have an inch of wool within a  month of shearing, with the important lanolin, it is only for around 4-6 weeks that they will need extra care if shorn in the winter

–          for welfare, it is also important that the weight of wool on a sheep in full fleece is considerable, particularly if wet, and this can lead to sheep getting stuck if they fall or to having soreness along the spin due to the fleece pulling down and the rain and weather affecting the stretched skin

–          in regard to quality, the benefits for processing of having cleaner fleeces which have not been dragged around in the mud, making up to a quarter of the length and certainly the tips almost unusable in some cases

–          longer fleeces also risk considerable vegetation contamination, which reduces quality and yield and there is a greater proportion of cotted/tangled/felted fleece, which cannot be processed.


Crimp is the waviness of the wool or hairs.  This ranges from tiny little ridges, such as found on Merino or Shetland, and huacaya alpacas, to longer waves, as on adult angora goats, suri alpacas and many of the longwool sheep, like Teeswater.  The crimp has many attributes of its own; from the number of crimps per unit length to the regularity, whether the whole hair also curves slightly and also the size of the crimps (ie the depth of the wave, as opposed to the swell!).

Crimp is very important to the memory of fibres, interestingly the fibre memory in sheep wool is greater than that in alpaca or goat hair, so that the resilience and elasticity of wool is also greater.  This, when combined with the thickness, can mean that some wool may feel quite crisp and crunchy when compared to mohair or alpaca of the same thickness.  This is increased by the more pronounced scales on wool hairs, as discussed above.

A comparison of Shetland, Devon and Cornwall Longwool and Southdown sheep.

A comparison of wool and alpaca.

As a result of this and its lower density, wool will produce a lighter, bouncier and more elastic yarn than mohair or alpaca. Wool yarns tend to knit up more economically, with a greater length of yarn per unit weight than mohair and alpaca.  Thus yarns made to the same specification of weight for length will also differ as to how lean or bulky they will be.

Crimp is also very individual to each breed of wool-producing sheep.  Each breed of sheep can usually be identified just by looking at the wool, so crimp is one of the key determinants of the style and appearance of the yarn we can make.

Lustre is the degree to which a fibre will reflect light and therefore how much it shines.  This is sometimes less easy to observe on a newly shorn fleece, which may shine due to its grease/lanolin content.  For example, Merino and downland wools generally have little lustre, while mohair, suri alpaca and longwools (such as Wensleydale and Cotswold) have considerable lustre.  In between these come the semi-lustre wools, such as Blue-faced Leicester and Romney. Some huacaya alpacas have lustre, though not all.

Natural lustre can be enhanced by aligning the fibres in a yarn, through worsted or semi-worsted spinning, so they have a greater opportunity to reflect light.  In addition, lustre wools will dye to more intense and brighter colours – this is the particular joy of mohair, which is the best of all at this!

Here is a comparison of lustre levels of some Blacker Yarns products, from highest to lowest lustre: Tamar in Red River, BFL Laceweight in Lightning Clownfish, Mohair Blends in Baripper and Blacker Swan in Mountain Berry.


Usefully, the lustre tends to correlate with greater length and density in the fibres, meaning that the elegance of greater drape can be achieved and also shown to its best advantage using silky lustre wools.